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3
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1 /* zlib.h -- interface of the 'zlib' general purpose compression library
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2 version 0.92 May 3rd, 1995.
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3
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4 Copyright (C) 1995 Jean-loup Gailly and Mark Adler
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5
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6 This software is provided 'as-is', without any express or implied
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7 warranty. In no event will the authors be held liable for any damages
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8 arising from the use of this software.
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9
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10 Permission is granted to anyone to use this software for any purpose,
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11 including commercial applications, and to alter it and redistribute it
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12 freely, subject to the following restrictions:
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13
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14 1. The origin of this software must not be misrepresented; you must not
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15 claim that you wrote the original software. If you use this software
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16 in a product, an acknowledgment in the product documentation would be
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17 appreciated but is not required.
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18 2. Altered source versions must be plainly marked as such, and must not be
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19 misrepresented as being the original software.
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20 3. This notice may not be removed or altered from any source distribution.
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21
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22 Jean-loup Gailly Mark Adler
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23 gzip@prep.ai.mit.edu madler@cco.caltech.edu
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24 */
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25
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26 #ifndef _ZLIB_H
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27 #define _ZLIB_H
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28
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29 #include "zconf.h"
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30
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31 #define ZLIB_VERSION "0.92"
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32
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33 /*
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34 The 'zlib' compression library provides in-memory compression and
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35 decompression functions, including integrity checks of the uncompressed
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36 data. This version of the library supports only one compression method
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37 (deflation) but other algorithms may be added later and will have the same
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38 stream interface.
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39
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40 For compression the application must provide the output buffer and
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41 may optionally provide the input buffer for optimization. For decompression,
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42 the application must provide the input buffer and may optionally provide
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43 the output buffer for optimization.
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44
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45 Compression can be done in a single step if the buffers are large
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46 enough (for example if an input file is mmap'ed), or can be done by
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47 repeated calls of the compression function. In the latter case, the
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48 application must provide more input and/or consume the output
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49 (providing more output space) before each call.
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50 */
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51
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52 typedef voidp (*alloc_func) __P((voidp opaque, uInt items, uInt size));
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53 typedef void (*free_func) __P((voidp opaque, voidp address));
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54
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55 struct internal_state;
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56
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57 typedef struct z_stream_s {
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58 Byte *next_in; /* next input byte */
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59 uInt avail_in; /* number of bytes available at next_in */
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60 uLong total_in; /* total nb of input bytes read so far */
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61
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62 Byte *next_out; /* next output byte should be put there */
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63 uInt avail_out; /* remaining free space at next_out */
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64 uLong total_out; /* total nb of bytes output so far */
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65
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66 char *msg; /* last error message, NULL if no error */
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67 struct internal_state *state; /* not visible by applications */
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68
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69 alloc_func zalloc; /* used to allocate the internal state */
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70 free_func zfree; /* used to free the internal state */
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71 voidp opaque; /* private data object passed to zalloc and zfree */
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72
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73 Byte data_type; /* best guess about the data type: ascii or binary */
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74
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75 } z_stream;
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76
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77 /*
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78 The application must update next_in and avail_in when avail_in has
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79 dropped to zero. It must update next_out and avail_out when avail_out
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80 has dropped to zero. The application must initialize zalloc, zfree and
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81 opaque before calling the init function. All other fields are set by the
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82 compression library and must not be updated by the application.
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83
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84 The opaque value provided by the application will be passed as the first
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85 parameter for calls of zalloc and zfree. This can be useful for custom
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86 memory management. The compression library attaches no meaning to the
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87 opaque value.
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88
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89 zalloc must return Z_NULL if there is not enough memory for the object.
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90 On 16-bit systems, the functions zalloc and zfree must be able to allocate
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91 exactly 65536 bytes, but will not be required to allocate more than this
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92 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
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93 pointers returned by zalloc for objects of exactly 65536 bytes *must*
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94 have their offset normalized to zero. The default allocation function
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95 provided by this library ensures this (see zutil.c). To reduce memory
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96 requirements and avoid any allocation of 64K objects, at the expense of
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97 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
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98
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99 The fields total_in and total_out can be used for statistics or
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100 progress reports. After compression, total_in holds the total size of
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101 the uncompressed data and may be saved for use in the decompressor
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102 (particularly if the decompressor wants to decompress everything in
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103 a single step).
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104 */
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105
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106 /* constants */
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107
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108 #define Z_NO_FLUSH 0
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109 #define Z_PARTIAL_FLUSH 1
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110 #define Z_FULL_FLUSH 2
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111 #define Z_FINISH 4
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112 /* See deflate() below for the usage of these constants */
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113
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114 #define Z_OK 0
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115 #define Z_STREAM_END 1
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116 #define Z_ERRNO (-1)
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117 #define Z_STREAM_ERROR (-2)
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118 #define Z_DATA_ERROR (-3)
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119 #define Z_MEM_ERROR (-4)
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120 #define Z_BUF_ERROR (-5)
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121 /* error codes for the compression/decompression functions */
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122
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123 #define Z_BEST_SPEED 1
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124 #define Z_BEST_COMPRESSION 9
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125 #define Z_DEFAULT_COMPRESSION (-1)
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126 /* compression levels */
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127
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128 #define Z_FILTERED 1
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129 #define Z_HUFFMAN_ONLY 2
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130 #define Z_DEFAULT_STRATEGY 0
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131
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132 #define Z_BINARY 0
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133 #define Z_ASCII 1
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134 #define Z_UNKNOWN 2
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135 /* Used to set the data_type field */
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136
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137 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
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138
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139 extern char *zlib_version;
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140 /* The application can compare zlib_version and ZLIB_VERSION for consistency.
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141 If the first character differs, the library code actually used is
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142 not compatible with the zlib.h header file used by the application.
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143 */
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144
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145 /* basic functions */
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146
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147 extern int deflateInit __P((z_stream *strm, int level));
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148 /*
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149 Initializes the internal stream state for compression. The fields
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150 zalloc, zfree and opaque must be initialized before by the caller.
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151 If zalloc and zfree are set to Z_NULL, deflateInit updates them to
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152 use default allocation functions.
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153
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154 The compression level must be Z_DEFAULT_COMPRESSION, or between 1 and 9:
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155 1 gives best speed, 9 gives best compression. Z_DEFAULT_COMPRESSION requests
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156 a default compromise between speed and compression (currently equivalent
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157 to level 6).
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158
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159 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
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160 enough memory, Z_STREAM_ERROR if level is not a valid compression level.
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161 msg is set to null if there is no error message. deflateInit does not
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162 perform any compression: this will be done by deflate().
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163 */
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164
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165
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166 extern int deflate __P((z_stream *strm, int flush));
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167 /*
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168 Performs one or both of the following actions:
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169
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170 - Compress more input starting at next_in and update next_in and avail_in
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171 accordingly. If not all input can be processed (because there is not
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172 enough room in the output buffer), next_in and avail_in are updated and
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173 processing will resume at this point for the next call of deflate().
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174
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175 - Provide more output starting at next_out and update next_out and avail_out
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176 accordingly. This action is forced if the parameter flush is non zero.
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177 Forcing flush frequently degrades the compression ratio, so this parameter
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178 should be set only when necessary (in interactive applications).
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179 Some output may be provided even if flush is not set.
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180
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181 Before the call of deflate(), the application should ensure that at least
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182 one of the actions is possible, by providing more input and/or consuming
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183 more output, and updating avail_in or avail_out accordingly; avail_out
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184 should never be zero before the call. The application can consume the
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185 compressed output when it wants, for example when the output buffer is full
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186 (avail_out == 0), or after each call of deflate().
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187
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188 If the parameter flush is set to Z_PARTIAL_FLUSH, the current compression
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189 block is terminated and flushed to the output buffer so that the
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190 decompressor can get all input data available so far. For method 9, a future
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191 variant on method 8, the current block will be flushed but not terminated.
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192 If flush is set to Z_FULL_FLUSH, the compression block is terminated, a
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193 special marker is output and the compression dictionary is discarded; this
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194 is useful to allow the decompressor to synchronize if one compressed block
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195 has been damaged (see inflateSync below). Flushing degrades compression and
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196 so should be used only when necessary. Using Z_FULL_FLUSH too often can
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197 seriously degrade the compression.
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198
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199 If the parameter flush is set to Z_FINISH, all pending input is processed,
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200 all pending output is flushed and deflate returns with Z_STREAM_END if there
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201 was enough output space; if deflate returns with Z_OK, this function must be
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202 called again with Z_FINISH and more output space (updated avail_out) but no
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203 more input data, until it returns with Z_STREAM_END or an error. After
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204 deflate has returned Z_STREAM_END, the only possible operations on the
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205 stream are deflateReset or deflateEnd.
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206
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207 Z_FINISH can be used immediately after deflateInit if all the compression
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208 is to be done in a single step. In this case, avail_out must be at least
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209 0.1% larger than avail_in plus 12 bytes. If deflate does not return
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210 Z_STREAM_END, then it must be called again as described above.
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211
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212 deflate() may update data_type if it can make a good guess about
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213 the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
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214 binary. This field is only for information purposes and does not affect
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215 the compression algorithm in any manner.
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216
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217 deflate() returns Z_OK if some progress has been made (more input
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218 processed or more output produced), Z_STREAM_END if all input has been
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219 consumed and all output has been produced (only when flush is set to
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220 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
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221 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
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222 */
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223
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224
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225 extern int deflateEnd __P((z_stream *strm));
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226 /*
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227 All dynamically allocated data structures for this stream are freed.
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228 This function discards any unprocessed input and does not flush any
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229 pending output.
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230
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231 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
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232 stream state was inconsistent. In the error case, msg may be set
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233 but then points to a static string (which must not be deallocated).
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234 */
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235
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236
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237 extern int inflateInit __P((z_stream *strm));
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238 /*
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239 Initializes the internal stream state for decompression. The fields
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240 zalloc and zfree must be initialized before by the caller. If zalloc and
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241 zfree are set to Z_NULL, deflateInit updates them to use default allocation
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242 functions.
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243
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244 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
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245 enough memory. msg is set to null if there is no error message.
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246 inflateInit does not perform any decompression: this will be done by
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247 inflate().
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248 */
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249
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250
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251 extern int inflate __P((z_stream *strm, int flush));
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252 /*
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253 Performs one or both of the following actions:
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254
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255 - Decompress more input starting at next_in and update next_in and avail_in
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256 accordingly. If not all input can be processed (because there is not
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257 enough room in the output buffer), next_in is updated and processing
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258 will resume at this point for the next call of inflate().
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259
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260 - Provide more output starting at next_out and update next_out and avail_out
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261 accordingly. inflate() always provides as much output as possible
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262 (until no more input data or no more space in the output buffer).
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263
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264 Before the call of inflate(), the application should ensure that at least
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265 one of the actions is possible, by providing more input and/or consuming
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266 more output, and updating the next_* and avail_* values accordingly.
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267 The application can consume the uncompressed output when it wants, for
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268 example when the output buffer is full (avail_out == 0), or after each
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269 call of inflate().
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270
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271 If the parameter flush is set to Z_PARTIAL_FLUSH, inflate flushes as much
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272 output as possible to the output buffer. The flushing behavior of inflate is
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273 not specified for values of the flush parameter other than Z_PARTIAL_FLUSH
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274 and Z_FINISH, but the current implementation actually flushes as much output
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275 as possible anyway.
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276
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277 inflate() should normally be called until it returns Z_STREAM_END or an
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278 error. However if all decompression is to be performed in a single step
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279 (a single call of inflate), the parameter flush should be set to
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280 Z_FINISH. In this case all pending input is processed and all pending
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281 output is flushed; avail_out must be large enough to hold all the
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282 uncompressed data. (The size of the uncompressed data may have been saved
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283 by the compressor for this purpose.) The next operation on this stream must
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284 be inflateEnd to deallocate the decompression state.
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285
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286 inflate() returns Z_OK if some progress has been made (more input
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287 processed or more output produced), Z_STREAM_END if the end of the
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288 compressed data has been reached and all uncompressed output has been
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289 produced, Z_DATA_ERROR if the input data was corrupted, Z_STREAM_ERROR if
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290 the stream structure was inconsistent (for example if next_in or next_out
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291 was NULL), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR if no
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292 progress is possible or if there was not enough room in the output buffer
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293 when Z_FINISH is used. In the Z_DATA_ERROR case, the application may then
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294 call inflateSync to look for a good compression block.
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295 */
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296
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297
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298 extern int inflateEnd __P((z_stream *strm));
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299 /*
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300 All dynamically allocated data structures for this stream are freed.
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301 This function discards any unprocessed input and does not flush any
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302 pending output.
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303
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304 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
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305 was inconsistent. In the error case, msg may be set but then points to a
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306 static string (which must not be deallocated).
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307 */
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308
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309 /* advanced functions */
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310
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311 /*
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312 The following functions are needed only in some special applications.
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313 */
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314
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315 extern int deflateInit2 __P((z_stream *strm,
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316 int level,
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317 int method,
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318 int windowBits,
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319 int memLevel,
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320 int strategy));
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321 /*
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322 This is another version of deflateInit with more compression options. The
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323 fields next_in, zalloc and zfree must be initialized before by the caller.
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324
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325 The method parameter is the compression method. It must be 8 in this
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326 version of the library. (Method 9 will allow a 64K history buffer and
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327 partial block flushes.)
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328
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329 The windowBits parameter is the base two logarithm of the window size
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330 (the size of the history buffer). It should be in the range 8..15 for this
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331 version of the library (the value 16 will be allowed for method 9). Larger
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332 values of this parameter result in better compression at the expense of
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333 memory usage. The default value is 15 if deflateInit is used instead.
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334
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335 The memLevel parameter specifies how much memory should be allocated
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336 for the internal compression state. memLevel=1 uses minimum memory but
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337 is slow and reduces compression ratio; memLevel=9 uses maximum memory
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338 for optimal speed. The default value is 8. See zconf.h for total memory
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339 usage as a function of windowBits and memLevel.
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340
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341 The strategy parameter is used to tune the compression algorithm. Use
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342 the value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data
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343 produced by a filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman
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344 encoding only (no string match). Filtered data consists mostly of small
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345 values with a somewhat random distribution. In this case, the
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346 compression algorithm is tuned to compress them better. The strategy
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347 parameter only affects the compression ratio but not the correctness of
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348 the compressed output even if it is not set appropriately.
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349
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350 If next_in is not null, the library will use this buffer to hold also
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351 some history information; the buffer must either hold the entire input
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352 data, or have at least 1<<(windowBits+1) bytes and be writable. If next_in
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353 is null, the library will allocate its own history buffer (and leave next_in
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354 null). next_out need not be provided here but must be provided by the
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355 application for the next call of deflate().
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356
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357 If the history buffer is provided by the application, next_in must
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358 must never be changed by the application since the compressor maintains
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359 information inside this buffer from call to call; the application
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360 must provide more input only by increasing avail_in. next_in is always
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361 reset by the library in this case.
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362
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363 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
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364 not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
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365 an invalid method). msg is set to null if there is no error message.
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366 deflateInit2 does not perform any compression: this will be done by
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367 deflate().
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368 */
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369
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370 extern int deflateCopy __P((z_stream *dest,
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371 z_stream *source));
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372 /*
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373 Sets the destination stream as a complete copy of the source stream. If
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374 the source stream is using an application-supplied history buffer, a new
|
|
|
375 buffer is allocated for the destination stream. The compressed output
|
|
|
376 buffer is always application-supplied. It's the responsibility of the
|
|
|
377 application to provide the correct values of next_out and avail_out for the
|
|
|
378 next call of deflate.
|
|
|
379
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|
|
380 This function is useful when several compression strategies will be
|
|
|
381 tried, for example when there are several ways of pre-processing the input
|
|
|
382 data with a filter. The streams that will be discarded should then be freed
|
|
|
383 by calling deflateEnd. Note that deflateCopy duplicates the internal
|
|
|
384 compression state which can be quite large, so this strategy is slow and
|
|
|
385 can consume lots of memory.
|
|
|
386
|
|
|
387 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
|
|
|
388 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
|
|
|
389 (such as zalloc being NULL). msg is left unchanged in both source and
|
|
|
390 destination.
|
|
|
391 */
|
|
|
392
|
|
|
393 extern int deflateReset __P((z_stream *strm));
|
|
|
394 /*
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|
|
395 This function is equivalent to deflateEnd followed by deflateInit,
|
|
|
396 but does not free and reallocate all the internal compression state.
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|
|
397 The stream will keep the same compression level and any other attributes
|
|
|
398 that may have been set by deflateInit2.
|
|
|
399
|
|
|
400 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
|
|
|
401 stream state was inconsistent (such as zalloc or state being NULL).
|
|
|
402 */
|
|
|
403
|
|
|
404 extern int inflateInit2 __P((z_stream *strm,
|
|
|
405 int windowBits));
|
|
|
406 /*
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|
|
407 This is another version of inflateInit with more compression options. The
|
|
|
408 fields next_out, zalloc and zfree must be initialized before by the caller.
|
|
|
409
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|
|
410 The windowBits parameter is the base two logarithm of the maximum window
|
|
|
411 size (the size of the history buffer). It should be in the range 8..15 for
|
|
|
412 this version of the library (the value 16 will be allowed soon). The
|
|
|
413 default value is 15 if inflateInit is used instead. If a compressed stream
|
|
|
414 with a larger window size is given as input, inflate() will return with
|
|
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415 the error code Z_DATA_ERROR instead of trying to allocate a larger window.
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416
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|
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417 If next_out is not null, the library will use this buffer for the history
|
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|
418 buffer; the buffer must either be large enough to hold the entire output
|
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|
419 data, or have at least 1<<windowBits bytes. If next_out is null, the
|
|
|
420 library will allocate its own buffer (and leave next_out null). next_in
|
|
|
421 need not be provided here but must be provided by the application for the
|
|
|
422 next call of inflate().
|
|
|
423
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|
|
424 If the history buffer is provided by the application, next_out must
|
|
|
425 never be changed by the application since the decompressor maintains
|
|
|
426 history information inside this buffer from call to call; the application
|
|
|
427 can only reset next_out to the beginning of the history buffer when
|
|
|
428 avail_out is zero and all output has been consumed.
|
|
|
429
|
|
|
430 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
|
|
|
431 not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
|
|
|
432 windowBits < 8). msg is set to null if there is no error message.
|
|
|
433 inflateInit2 does not perform any compression: this will be done by
|
|
|
434 inflate().
|
|
|
435 */
|
|
|
436
|
|
|
437 extern int inflateSync __P((z_stream *strm));
|
|
|
438 /*
|
|
|
439 Skips invalid compressed data until the special marker (see deflate()
|
|
|
440 above) can be found, or until all available input is skipped. No output
|
|
|
441 is provided.
|
|
|
442
|
|
|
443 inflateSync returns Z_OK if the special marker has been found, Z_BUF_ERROR
|
|
|
444 if no more input was provided, Z_DATA_ERROR if no marker has been found,
|
|
|
445 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
|
|
|
446 case, the application may save the current current value of total_in which
|
|
|
447 indicates where valid compressed data was found. In the error case, the
|
|
|
448 application may repeatedly call inflateSync, providing more input each time,
|
|
|
449 until success or end of the input data.
|
|
|
450 */
|
|
|
451
|
|
|
452 extern int inflateReset __P((z_stream *strm));
|
|
|
453 /*
|
|
|
454 This function is equivalent to inflateEnd followed by inflateInit,
|
|
|
455 but does not free and reallocate all the internal decompression state.
|
|
|
456 The stream will keep attributes that may have been set by inflateInit2.
|
|
|
457
|
|
|
458 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
|
|
|
459 stream state was inconsistent (such as zalloc or state being NULL).
|
|
|
460 */
|
|
|
461
|
|
|
462
|
|
|
463 /* utility functions */
|
|
|
464
|
|
|
465 /*
|
|
|
466 The following utility functions are implemented on top of the
|
|
|
467 basic stream-oriented functions. To simplify the interface, some
|
|
|
468 default options are assumed (compression level, window size,
|
|
|
469 standard memory allocation functions). The source code of these
|
|
|
470 utility functions can easily be modified if you need special options.
|
|
|
471 */
|
|
|
472
|
|
|
473 extern int compress __P((Byte *dest, uLong *destLen,
|
|
|
474 Byte *source, uLong sourceLen));
|
|
|
475 /*
|
|
|
476 Compresses the source buffer into the destination buffer. sourceLen is
|
|
|
477 the byte length of the source buffer. Upon entry, destLen is the total
|
|
|
478 size of the destination buffer, which must be at least 0.1% larger than
|
|
|
479 sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
|
|
|
480 compressed buffer.
|
|
|
481 This function can be used to compress a whole file at once if the
|
|
|
482 input file is mmap'ed.
|
|
|
483 compress returns Z_OK if success, Z_MEM_ERROR if there was not
|
|
|
484 enough memory, Z_BUF_ERROR if there was not enough room in the output
|
|
|
485 buffer.
|
|
|
486 */
|
|
|
487
|
|
|
488 extern int uncompress __P((Byte *dest, uLong *destLen,
|
|
|
489 Byte *source, uLong sourceLen));
|
|
|
490 /*
|
|
|
491 Decompresses the source buffer into the destination buffer. sourceLen is
|
|
|
492 the byte length of the source buffer. Upon entry, destLen is the total
|
|
|
493 size of the destination buffer, which must be large enough to hold the
|
|
|
494 entire uncompressed data. (The size of the uncompressed data must have
|
|
|
495 been saved previously by the compressor and transmitted to the decompressor
|
|
|
496 by some mechanism outside the scope of this compression library.)
|
|
|
497 Upon exit, destLen is the actual size of the compressed buffer.
|
|
|
498 This function can be used to decompress a whole file at once if the
|
|
|
499 input file is mmap'ed.
|
|
|
500
|
|
|
501 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
|
|
|
502 enough memory, Z_BUF_ERROR if there was not enough room in the output
|
|
|
503 buffer, or Z_DATA_ERROR if the input data was corrupted.
|
|
|
504 */
|
|
|
505
|
|
|
506
|
|
|
507 typedef voidp gzFile;
|
|
|
508
|
|
|
509 extern gzFile gzopen __P((char *path, char *mode));
|
|
|
510 /*
|
|
|
511 Opens a gzip (.gz) file for reading or writing. The mode parameter
|
|
|
512 is as in fopen ("rb" or "wb"). gzopen can also be used to read a file
|
|
|
513 which is not in gzip format; in this case gzread will directly read from
|
|
|
514 the file without decompression.
|
|
|
515 gzopen returns NULL if the file could not be opened or if there was
|
|
|
516 insufficient memory to allocate the (de)compression state; errno
|
|
|
517 can be checked to distinguish the two cases (if errno is zero, the
|
|
|
518 zlib error is Z_MEM_ERROR).
|
|
|
519 */
|
|
|
520
|
|
|
521 extern gzFile gzdopen __P((int fd, char *mode));
|
|
|
522 /*
|
|
|
523 gzdopen() associates a gzFile with the file descriptor fd. File
|
|
|
524 descriptors are obtained from calls like open, dup, creat, or pipe.
|
|
|
525 The mode parameter is as in fopen ("rb" or "wb").
|
|
|
526 gzdopen returns NULL if there was insufficient memory to allocate
|
|
|
527 the (de)compression state.
|
|
|
528 */
|
|
|
529
|
|
|
530 extern int gzread __P((gzFile file, voidp buf, unsigned len));
|
|
|
531 /*
|
|
|
532 Reads the given number of uncompressed bytes from the compressed file.
|
|
|
533 If the input file was not in gzip format, gzread copies the given number
|
|
|
534 of bytes into the buffer.
|
|
|
535 gzread returns the number of uncompressed bytes actually read (0 for
|
|
|
536 end of file, -1 for error). */
|
|
|
537
|
|
|
538 extern int gzwrite __P((gzFile file, voidp buf, unsigned len));
|
|
|
539 /*
|
|
|
540 Writes the given number of uncompressed bytes into the compressed file.
|
|
|
541 gzwrite returns the number of uncompressed bytes actually written
|
|
|
542 (0 in case of error).
|
|
|
543 */
|
|
|
544
|
|
|
545 extern int gzflush __P((gzFile file, int flush));
|
|
|
546 /*
|
|
|
547 Flushes all pending output into the compressed file. The parameter
|
|
|
548 flush is as in the deflate() function. The return value is the zlib
|
|
|
549 error number (see function gzerror below). gzflush returns Z_OK if
|
|
|
550 the flush parameter is Z_FINISH and all output could be flushed.
|
|
|
551 gzflush should be called only when strictly necessary because it can
|
|
|
552 degrade compression.
|
|
|
553 */
|
|
|
554
|
|
|
555 extern int gzclose __P((gzFile file));
|
|
|
556 /*
|
|
|
557 Flushes all pending output if necessary, closes the compressed file
|
|
|
558 and deallocates all the (de)compression state. The return value is the zlib
|
|
|
559 error number (see function gzerror below).
|
|
|
560 */
|
|
|
561
|
|
|
562 extern char* gzerror __P((gzFile file, int *errnum));
|
|
|
563 /*
|
|
|
564 Returns the error message for the last error which occurred on the
|
|
|
565 given compressed file. errnum is set to zlib error number. If an
|
|
|
566 error occurred in the file system and not in the compression library,
|
|
|
567 errnum is set to Z_ERRNO and the application may consult errno
|
|
|
568 to get the exact error code.
|
|
|
569 */
|
|
|
570
|
|
|
571 /* checksum functions */
|
|
|
572
|
|
|
573 /*
|
|
|
574 These functions are not related to compression but are exported
|
|
|
575 anyway because they might be useful in applications using the
|
|
|
576 compression library.
|
|
|
577 */
|
|
|
578
|
|
|
579 extern uLong adler32 __P((uLong adler, Byte *buf, uInt len));
|
|
|
580 /*
|
|
|
581 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
|
|
|
582 return the updated checksum. If buf is NULL, this function returns
|
|
|
583 the required initial value for the checksum.
|
|
|
584 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
|
|
|
585 much faster. Usage example:
|
|
|
586
|
|
|
587 uLong adler = adler32(0L, Z_NULL, 0);
|
|
|
588
|
|
|
589 while (read_buffer(buffer, length) != EOF) {
|
|
|
590 adler = adler32(adler, buffer, length);
|
|
|
591 }
|
|
|
592 if (adler != original_adler) error();
|
|
|
593 */
|
|
|
594
|
|
|
595 extern uLong crc32 __P((uLong crc, Byte *buf, uInt len));
|
|
|
596 /*
|
|
|
597 Update a running crc with the bytes buf[0..len-1] and return the updated
|
|
|
598 crc. If buf is NULL, this function returns the required initial value
|
|
|
599 for the crc. Pre- and post-conditioning (one's complement) is performed
|
|
|
600 within this function so it shouldn't be done by the application.
|
|
|
601 Usage example:
|
|
|
602
|
|
|
603 uLong crc = crc32(0L, Z_NULL, 0);
|
|
|
604
|
|
|
605 while (read_buffer(buffer, length) != EOF) {
|
|
|
606 crc = crc32(crc, buffer, length);
|
|
|
607 }
|
|
|
608 if (crc != original_crc) error();
|
|
|
609 */
|
|
|
610
|
|
|
611 #ifndef _Z_UTIL_H
|
|
|
612 struct internal_state {int dummy;}; /* hack for buggy compilers */
|
|
|
613 #endif
|
|
|
614
|
|
|
615 #endif /* _ZLIB_H */
|
